Traditionally, motion picture film stock cores, such as those defined by the Society of Motion Picture and Television Engineers (SMPTE) standard ANSI-SMPTE 37M or ISO 1039-1995, have been injection molded from thermoplastic high impact polystyrene (HIPS) molding compounds. The HIPS resin has been the material of choice mostly driven by cost, ease of injection molding, and suitability for the state of motion picture film production and cinema projection technology. Cores produced from HIPS resins have been used to produce motion picture cores from multi-cavity tools or molds now for over forty years.
Over time the total amount (as measured in length) of motion picture film and the tightness of wrap (with a resultant hoop stress on the core) has increased. The spooling process (manufacturing and printing) has evolved into a high-speed process where motion picture film is spooled at a speed of thousands of meters per minute to achieve greater productivity rates. A result of these improvements is a finished core product with a much greater weight and stress but with no change in the basic design of the motion picture core to compensate. Moreover, the demands of cinematographers for low light sensitive films and the demands from consumers for high-quality theatre experience have increased demands for film cleanliness in raw stock and printing production. The high speed of the spooling process combined with the poor overall wear property of the current thermoplastic HIPS resin result in the generation of a tremendous amount of HIPS dust and debris at the mounting interface of the core with the winding machine spindle. The generation of this level of debris creates high production losses and nightmarish housekeeping issues. The present invention resolves all of these issues plus creates an opportunity of reuse of cores which was never done with the HIPS resins due to the potential of damage from handling, transportation and use. Core crush, a form of permanent deformation, is exemplary of the damage from handling where a fully spooled motion picture core sustains sufficient impact energy to literally crush the core resulting in complete failure of the part. Needless to say, this form of damage is particularly costly and frustrating to motion picture printing customers because: 1) film telescopes and comes off of whatever is left of the damaged core; and/or 2) the core cannot be installed onto the winding spindle.
There have been several attempts in the art to solve aspects of the above problems. In U.S. Pat. No. 4,042,399 by Kiesslich teaches the disclosure of a photographic element having improved slip. However, a shortcoming of this development is that the surface of the photographic element is required to be coated with a polyester film to improve slip.
Another prior art film transport development is described in U.S. Pat. No. 5,694,629 by Stephenson, III et al. The transport mechanism of Stephenson uses slip clutches made of polycarbonate to improve slip.
In U.S. Pat. No. 4,049,861 by Nozari a web-winding device is disclosed that requires the use of abrasion resistant coatings including polyesters and polycarbonates to reduce web slippage.
Therefore, a need persists in the art for a web-winding means that has a mounting surface with substantially reduced friction, is substantially damage resistant, and does not generate deleterious debris during typical web-winding and unwinding operations.